This research aims to evaluate the urban heat island intensity (UHII) and study the
influences of population density, building density, and traffic density on the UHII in
Chiang Mai city on each season and time. The surrounding air temperature was
measured by thermocouples at a constant height of 2 m above the road by mobile
surveying approach. The surveyed routes were divided into urban routes and rural
routes. The UHII was calculated from the average surrounding air temperature difference
between the urban and the rural areas. Experimental investigations were
carried out in two seasons, consisting of summer (March-May, 2014) and winter
(December 2013-February 2014). Experimental investigations were carried out in
two periods, which were a daytime period (01.00-03.00 p. m.) and a nighttime period
(10.00 p. m.-00.00 a. m.) on Mondays, Wednesdays, and Sundays. The results
show that the UHII in summer day, summer night, winter day, and winter night were
1.07 °C, 1.27 °C, 0.58 °C, and 1.34 °C, respectively. This implies that the temperature
in Chiang Mai city's urban area is higher than that in the rural area the entire
year. Moreover, it was found that the UHII in summer day, winter day, and winter
night were primarily affected by the traffic density with the sensitivity percentage of
87.50%, 72.73%, and 63.33%, respectively. In contrast, the UHII in summer night
was mainly affected by the building density with the sensitivity percentage of
50.00%.